This invention relates to a novel reinforcing composition for reinforcing natural or artificial mineral structures such as natural structures made of rocks or minerals and artificial structures made of ceramics, artificial stones, concrete or mortar as well as the surface structures of the earth such as road surfaces or sloping surfaces. More particularly, this invention relates to a novel reinforcing composition and method that uses the mineral material per se to be reinforced as one of the polymerization initiating ingredients.
Hitherto, methods suggested for reinforcing shaped mineral products such as concrete block and ceramic products include a method wherein such shaped mineral products are impregnated with a monomer and irradiated by actinic rays to cause polymerization of the monomer, a method wherein such shaped mineral structures are impregnated with a monomer to which a radical-polymerization initiator has been added and then are heated to cause polymerization of the monomer, and like methods. As these methods require radiation by actinic rays or heating, however, the articles to be treated are limited in size according to the size of the treating apparatus and such methods are utterly inapplicable to reinforcement or repair of natural or artificial structures located in the field.
Earth strengthening agents composed predominantly of cement or sodium silicate are known in the art. In the case of the agents composed predominantly of cement, however, the cement particles contained therein cannot penetrate through layers of earth having voids smaller in diameter than the particles. Therefore, agents based on cement particles cannot be usefully applied to a layer of fine sand. In addition, the impossibility of controlling the hardening time of cement makes such agents unsuited for injection hardening of the earth where water springs or sand flows. On the other hand, in previous agents composed predominantly of sodium silicate, the sodium silicate must be present in high concentration to achieve good hardening of the earth and can undergo initiation of a rapid reaction to give too high viscosity to be applicable to strata of finely particulate sand. Further permeation and hardening of agents of the latter type is unpredictable because of natural variations in the earth, such as chemical composition, earth temperature or moisture content.
For treating sloping earth surface, some chemical grouts are known which contain urea resin or urethane resin as their base. However, these grouts are difficult to handle because of their high viscosity and are limited in the application to the earth depending on its nature.
Some earth stabilizing agents based on a water-soluble monomer such as an acrylic salt or acrylamide have been proposed heretofore to improve the above mentioned defects of chemical grouts based on urea or urethane resins. However, these stabilizing agents also have disadvantages; they require a Redox catalyst system that is difficult to prepare and their application is narrowly limited because the monomers that can be utilized are limited. Thus, there is a real need for earth-treating agents that can overcome these defects and can be used widely for treating shaped mineral structures and earth surfaces.